Date:         Wed, 30 Nov 2011 19:10:53 -0800
Reply-To:     "Jordan, Lewis" <Lewis.Jordan@WEYERHAEUSER.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Jordan, Lewis" <Lewis.Jordan@WEYERHAEUSER.COM>
Subject:      Re: Unable to fit the model with PROC NLIN
Comments: To: SUBSCRIBE SAS-L Anonymous <rkbattula@DRREDDYS.COM>
In-Reply-To:  <201111300945.pAU2kqaZ025468@waikiki.cc.uga.edu>
Content-Type: text/plain; charset="us-ascii"

P.S. Get rid of the derivatives statement. NLIN is now smart enough that it can compute these for you...


*****************************
Lewis Jordan
Weyerhaeuser:
Southern Timberlands Group
Cell (Primary): 662-889-4514
Office: 662-245-5227
lewis.jordan@weyerhaeuser.com
*****************************
________________________________________
From: SAS(r) Discussion [SAS-L@LISTSERV.UGA.EDU] On Behalf Of SUBSCRIBE SAS-L Anonymous [rkbattula@DRREDDYS.COM]
Sent: Wednesday, November 30, 2011 3:45 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Unable to fit the model with PROC NLIN

Hi every body,

I tried to fit the model with three observations. I have three different
doses and their PD responses. I used following code:

proc nlin data = it method=marquardt hougaard;
 parms E0 =1  ED50 =1  Emax = 1 ;  parameters;
 model FFEP=E0 + ((Emax * Dose) / (ED50 + Dose));
 Der.E0   = 1;
 Der.Emax = Dose / ( ED50 + Dose);
 Der.ED50 = - (( Emax * Dose)/ ((ED50 + Dose)**2));
 output out=pred p=yhat;
run;

Model is not able to fit since I have only three observations. Is there
any way to work on this? Your help is greatly appriciated.

Thanks,

krishna.